A three-wheeled electric powered chair in public use in the United States is manufactured by Fortress Scientific of Hayes Road, Southall, Middlesex, England UB2 5LZ. This chair has steering handle bars forward of the chair seat and forward and reverse control lever arms mounted behind the handle bars for actuation by the thumbs of the occupant having his hands on the bars.
When both the thumb lever arms are released they automatically return to power-off or neutral position, automatically stopping the vehicle by means of electric dynamic braking of the drive, but the electric battery power is still connected through a main key switch in readiness for the next operation. Accordingly, if the occupant rises to dismount without turning off the main switch he is quite likely to accidentally bump one of the thumb lever arms causing the chair to lurch forward or reverse and resulting in serious injury to the occupant by throwing him to the floor or ground.
The precaution of turning off the main switch is easily forgotten or overlooked if the occupant rises in haste to answer the telephone or doorbell, for example.